The present invention relates generally to sun visors installed in cars or airplane cockpits for filtering or blocking sunlight coming in through the car or cockpit windows. More particularly, it concerns such a sun visor mounted on a monorail with a locking carriage assembly that allows a user to move the sun visor along the monorail, to lock the sun visor in any selected position, and to move the sun visor to an end of the monorail where it may be flipped to a detented, upper position away from the windows.
Applicant is the inventor of the sun visor system described in U.S. Pat. No. 5,056,854, which is a monorail-mounted sun visor system. The monorail is installed in a car or airplane cockpit, preferably just above the windows. The sun visor includes a mounting structure for mounting the sun visor on the monorail. The mounting structure includes jaws contacting the monorail and a panel is connected to the mounting structure. The mounting structure may be selectively locked onto or released from the monorail by operating a knob which turns a screw that tightens or loosens the jaws. This sun visor system provides a convenient, adjustable sunvisor but, it has drawbacks as well. The screw-tightened jaws are prone to loosening inadvertently in the highly vibratory environment of the car or airplane. Although the knob is quite large, giving the user a strong mechanical advantage for tightening the screw, loosening is still a problem and extreme tightening of the screw may make it difficult for the next user of the sun visor to adjust the sun visor position. Furthermore, the mechanical advantage of the knob and screw is only obtained at the cost of requiring the user to turn the knob several times around to adjust between the tightened and loosened positions.
Another drawback is encountered when the visor is flipped up to a fixed, stowed position, as desirable at times in cars and as required in airplane cockpits by the FAA for takeoffs and landings: The sun visor is moved from a deployed position to the stowed position, in a two-handed operation that involves loosening the jaws, flipping the visor up and then tightening the jaws. However, when the visor is flipped up, the knob for tightening the jaws is adjacent the car ceiling or cockpit bulkhead on a side of the jaws facing away from the user, increasing the difficulty of tightening the knob.
What would be preferable is a sun visor mounted on a monorail, providing the maximum flexibility in positioning, that can be locked in place at any selected position on the monorail by a simple, locking handle. The handle would be operable in a simple motion, like a light switch or door knob, but would provide for a positive lock of the sun visor on the monorail. The switch would preferably also provide a total of three positions: (1) a locked position in which the sun visor is substantially fixed in an axial position by a brake along the monorail but, with a leverage advantage obtained by gripping an edge of the visor panel opposite the monorail, the sun visor is also rotatable about the monorail; (2) an intermediate, partially-released position in which the sun visor may be easily moved along or rotated about the monorail while the brake remains in frictional contact with the monorail; and (3) a fully-released position in which the brake is withdrawn from the monorail completely. The monorail is preferably made of a simple, ungated, unitary structure. Another desirable feature in a sun visor would be a structure that provided for flipping the visor up to a detent-fixed, stowed position where the visor may be easily locked in place.
The sun visor of the present invention provides all of these advantages and more. The monorail structure for mounting the sun visor is constructed of an elongate, rigid structure, such as a steel rod having mounting tabs welded thereon for attaching the monorail to the car ceiling or airplane cockpit bulkhead. The monorail is installed around at least the front and sides of the car or cockpit. The sunvisor includes a mounting structure which is coupled to two gripping members with opposed surfaces. The gripping members are mountable on the monorail. A panel frame is coupled to the mounting structure and a visor panel, made of a deeply tinted plastic or glass or an opaque material, is held by the panel frame so that, when the gripping members are mounted on the monorail, the visor panel nominally hangs down adjacent the car or cockpit windows. The visor panel thus advantageously provides a filter or block that can be positioned anywhere sunlight interferes with the driver's or pilot's vision.
The mounting structure includes a mounting mechanism supporting the gripping members and a locking mechanism coupled to the gripping members. Each of the gripping members is supported separately by the mounting mechanism so that each may move independently of the other, although, preferably, the locking mechanism is designed to move the gripping members simultaneously in opposite directions to grip or to release the monorail. The locking mechanism includes a rotatable handle, operable by the user to move the gripping members between the three positions: locked, intermediate, and fully withdrawn. The handle is coupled to a cam mechanism which transforms the rotation of the handle into a translational braking force on the gripping members. The cam mechanism includes front, middle, and rear wheels coaxially coupled by a shaft. The front wheel is welded to the handle. A first dowel pin extends perpendicularly between the front and middle wheels, parallel to, but offset from, the shaft. A second dowel pin extends perpendicularly between the middle and rear wheels, also parallel to, but offset from, the shaft. The dowel pins are positioned and coupled to the gripping members so that, when the handle is turned, one dowel pin moves up and the other dowel pin moves down, causing the gripping members to move in opposite directions.
In the fully withdrawn position, the dowel pins are side by side, on opposite sides of the shaft, lying in a plane roughly parallel to the monorail, and the gripping members are fully retracted from the monorail. As the handle is turned toward the intermediate position, which is approximately 45.degree. from the fully withdrawn position, the dowel pin coupled to the lower gripping member moves up and the dowel pin coupled to the upper gripping member moves down, causing the gripping members to grip the monorail. A spring biases the gripping members to the intermediate position.
Moving the handle to the locked position, which is about 90.degree. from the fully withdrawn position, causes the gripping members to tighten their grip on the monorail. As the grip tightens, the gripping members and monorail press together, producing a force reactive to the braking or gripping force which tends to force the gripping members apart. Prior to the handle reaching the locked position, the reactive force also tends to oppose the rotation of the handle. However, when the handle reaches the locked position, about 90.degree. from the fully withdrawn position, with the dowel pins lying in a plane perpendicular to the monorail, the reactive force is perpendicular to the tangent of the rotational force and so the reactive force no longer has a component opposing the rotational force. As the handle is rotated slightly further, past the 90.degree. position, the reactive force has a component that actually increases the rotational force, ensuring that the handle and gripping members will remain in the locked position.
At one end of the monorail, a rail stop is installed including a fixed member adapted to be rigidly mounted on the monorail and a rotatable member pivotally coupled to the fixed member. The stop includes a detent mechanism interposing the fixed and rotatable members that fixes the rotatable member in place at any of two or more selectable positions relative to the fixed member. The rotatable member also includes a coupling member for engaging the mounting mechanism of the sun visor to control rotation of the sun visor about the monorail.
A significant advantage of the sun visor of the present invention is that the user may quickly and easily rotate the handle just a quarter turn from the fully-released position to the locked position to secure the visor in place. Another advantage is that in the locked position, the gripping members will not release their grip on the monorail despite vibration that would cause a hand-tightened screw to back out.
Another appreciable advantage of the invention is that the user may slide the sun visor into the coupling member of the rail stop and flip the visor panel up to a detented, stowed position and back down to a deployed position. With the sun visor at the rail stop, but down in the deployed position, the user may position the handle to the locked position and then flip the sun visor up to the stowed position. The locked position of the handle prevents axial movement of the sun visor along the monorail, so, the sun visor remains engaged by the coupling member of the rail stop and the rail stop prevents rotational movement of the sun visor about the monorail unless the detent is overcome.
A further advantage of the present invention is that, with the handle in the spring-loaded intermediate position, a user may freely slide the sun visor around the car or cockpit. This position is adequate to hold frictionally the sun visor in place on the rail under most transient conditions. For higher g-forces, the sun visor may be locked in place with just a one-eighth turn of the handle.
These and additional objects and advantages of the present invention will be more readily understood after a consideration of the drawings and the detailed description of the preferred embodiment.